This invention relates generally to dynamic profiling systems for measuring a profile of an outer surface of a moving motor component such as a motor commutator and relates more particularly to a computer controlled dynamic profiling system that automatically positions a liquid cooled data collecting probe in close proximity with the outer surface of a rotating motor component.
Large motor components such as commutators are typically used in electrical motors for propulsion systems. The commutators are typically constructed from copper segments or bars laminated and stacked in a circular arrangement so that armature coils may be connected to each of the segments. Each stack is separated by a layer of insulating material so that each stack is electrically isolated from the adjacent stack. The stacked segments form a thick cylinder with the outside surface of the cylinder forming tracks against which multiple fixed brushes contact.
The stacked segments are constructed to create vertical "bars" projecting radially from the center of the commutator and are substantially flush with the outer surface of the cylinder. A large number of vertical bars are evenly spaced around the circumference of the commutator. The number of bars in a commutator typically range from 97 to 250 bars depending upon the physical dimensions of the commutator.
The run-out of the commutator is the physical deformation from bar to bar and is an indication of how the commutator will perform when fitted on armatures and operated in the field. A profile is the measurement of the physical deformation of the bars in the commutator. A profile includes information pertaining to each bar, the bar-to-bar variation, and multiple profiles may be presented in tabular or graphical form. In the past, static and dynamic testing of commutators has been performed.
Conventional static testing systems generally use a mechanical probe or proximity probe to measure the run-out of the commutator along a brush track. The commutator is slowly rotated either manually or mechanically at approximately one to two revolutions per minute. A probe is aligned against the outer surface of the slowly rotating commutator by an operator and a strip chart output is created reflecting the variation from bar to bar. The strip chart output is analyzed and any particular bar showing an abnormal amount of variation is mechanically reduced so as to conform to required parameters. The static test is then repeated to determine if the run-out variation is within acceptable parameters. This process is repeated until all of the bars are within specification.
A problem arises with static testing since it is slow and typically labor intensive. Additionally, static profiling does not indicate how the commutator will react at various speeds and at various temperatures. Since static profiling only yields profile information when the commutator is essentially stationary and at ambient temperature, physical variations and defects apparent during rotational rates experienced in the field cannot be detected. Additionally, static profiling does not provide an indication of how the different brush tracks react at various speeds and temperatures, nor is there any indication of what effect these variations could have on motor performance. Thus, static testing does not provide a true indication of how the commutator will perform in this field.
To address some of the deficiencies associated with static profile testing, manual dynamic profiling has been employed and is well known in the art. Typically, under manual dynamic testing, the commutator is rotated at approximately 2940 revolutions per minute. However, the commutator may be rotated at rates up to 4000 revolutions per minute. Once the commutator is rotating at the required speed, a profile is measured with a proximity probe while the commutator is at ambient temperature.
Manual dynamic profiling systems typically use a proximity probe to produce an electrical signal which is then displayed on an oscilloscope. A photograph is then taken of the oscilloscope trace and various data such as time, date, commutator temperature, commutator speed, and brush track number is hand-written on the photograph. The photographic oscilloscope trace is then analyzed to determine which bars show excessive variation. The bars which do not meet the required specifications are physically reduced and the process is repeated until all of the bars in the commutator are within the required tolerances.
Manual dynamic profiling is superior to static profiling since variations can be detected while the commutator is rotating at speeds representative of normal operating speeds. However, manual dynamic profiling still has serious disadvantages. Manual dynamic profiling requires a dedicated and highly trained operator to calibrate and control the equipment. Once the photographs have been produced, additional engineering personnel are required to interpret the data. This method is extremely time consuming and expensive.
In the past, manual dynamic profiling systems have used computer controlled proximity probes. Most of the proximity probes were adequate for cold profiling (at ambient temperature), however, the proximity probes typically did not function properly and degraded rapidly when subject to the temperatures developed when the commutator was heated. Laser light probes have also been used to gather profile data in a heated environment since close proximity to the heated commutator was not required. However, laser probes have also been unsuccessful due to the effects of the high temperatures on data collection performance.
Methods of cooling the probe while operating in above ambient temperature environments have been developed. Typically, the probe is surrounded by a water bath that is radiantly cooled. The surrounding structure forms a jacket around the probe and is filled with a fixed or static volume of water. The water jacket is cooled by convection and can satisfactorily cool the probe when the temperature of the commutator is maintained below approximately 60.degree. centigrade. When the temperature is increased beyond 60.degree. centigrade, the heat dissipated by the water jacket is typically less than the heat absorbed by the probe. Therefore, the water within the water jacket begins to increases in temperature. However, such systems typically cannot facilitate high temperature testing above the 60.degree. centigrade level. When multiple tests are performed, the operator must recalibrates the equipment to account for the increase in heat since the profile measurements are affected by the increased temperature of the probe. This process is expensive, time consuming, and is prone to inaccuracies. Thus, a need exists for a dynamic profiling device capable of operating at high temperatures such as above 160.degree. centigrade. These high temperatures are closer to the operating temperature of the motor components so that operating condition testing may be facilitated.
Prior art dynamic profiling systems also present potentially dangerous safety hazards. Typically, the commutator is rotated at a rate of 2900 to 4000 revolutions per minute. The combination of high temperature and centrifugal forces created by the high spin rate occasionally cause the commutator to break apart or explode. Should this occur, small fragments and large chunks of the commutator could be ejected at high speeds from the test platform. This poses a serious risk to personnel and property in the test vicinity. Thus, the need exists for a protective environment in which to test the rotating commutator while still allowing for access to the commutator by the probe while the commutator is at high temperatures.
Thus, it is an object of the present invention to provide an automatic dynamic commutator profiling system that substantially overcomes the above problems.
It is another object of the present invention to provide a dynamic commutator profiling system to test a commutator under hot and ambient conditions.
It is still another object of the present invention to provide a computer controlled dynamic commutator profiling system to collect, analyze, and display profiling data.
It is yet another object of the invention to provide a dynamic commutator profiling system with a probe cooling system for maintaining the probe at a fixed temperature when the probe is subject to high temperatures developed when the commutator is heated.
It is a further object of the invention to provide a dynamic commutator profiling system with a probe that is automatically controlled by a controller for positioning along various brush tracks.
It is a yet another object of the invention to provide an improved dynamic commutator profiling system with an aperture, and a controllable door attached to a protective enclosure to allow probe access to the rotating motor component to facilitate high temperature testing.